Apparatus for coating metallic materials



July 18, 1939. J. 1.. HERMAN APPARATUS FOR COATING METALLIC MATERIALS IP V i1 all.

Filed Dec. 5, 1954 INZ'SZENTCIIIFL.

1 I 5 5.11 1 5: n I u 'ATIY.

Patented July 18, 1939 UNITED STATES tPATENT OFFICE APPARATUS FORCOATING METALLIC MATER IALS 4 Claims.

This invention has reference to an apparatus for applying metalliccoatings to iron or steel articles.

More specifically the invention has reference to an apparatus forcoating iron or steel articles with zinc spelter to produce a heavycoating which is low in iron, substantially free from oxides, scruff ordeleterious matter, bright, smooth and of uniform thickness throughout,which coating will withstand severe deforming without dusting, flaking,cracking or peeling. Furthermore, a coating low in iron, such as Iproduce, is ductile and high in electrical conductivity, and

is therefore-useful in the production of telephone wire.

To produce a zinc coated iron or steel article with a coating low iniron, it is desirable that the article be removed from the zinc bathbefore the article base reaches the temperature of the bath, or at leastbefore the coating becomes high in iron. This time element is determinedby the temperature of. the bath, the length of time the material is inthe bath and the rapidity with which the coated article is cooled.

To produce a zinc coating on an iron or steel article free from oxidesor other deleterious matter, the article should be withdrawn from thebath through an oxide free surface and to remove the possibility thatany particle of oxides shall adhere to the surface of the article, whereit enters the bath, provision should be made for introducing the articleinto the bath through an oxide free surface. In the accomplishment of anoxide free surface on the bath in the area of the emergence of thecoated article from the'bath, I employ the use of a ngn-oxidizing gaswhich is applied to the bath where the article emerges therefrom, so asto provide a seal and preferably cause the article to be moved throughan oxygen free atmosphere and to be immediately quenched when leavingsaid atmosphere, and to remove from the body of the bath, and from belowits surface, oxide free zinc and cause it to be moved across the articlebeing coated arid down and around the article, so as to insure thearticle emerging from the bath through an oxide free surface.

By the use of my apparatus, i am able to produce a zinc coated articlewhere the coating is heavy and low in iron; where both the surface ofthe article, and the body and the surface of the coating aresubstantially oxide free and having a silvery bright appearance.

I have found from long experience in the guivanizing of iron or steelarticles, that a zinc coating which is relatively high in iron, as forexample 7% or higher, is more or less brittle and will not withstand theordinary deforming galvanized articles are subjected to, with the resultthat the coating will flake, peel, crack or dust, resulting in earlydeterioration of the article, impairing its usefulness. By my apparatusI reduce the iron content usually present in zinc coatings by subjectingthe article to a short immersion in the molten bath, passing the articlethrough the bath at a. relatively high speed and rapidly quenching thecoated article. This is preferably accomplished through the use of asmaller pot than ordinarily used and increasing the speed of the article.through the pot, over the speeds ordinarily used. This is especiallytrue in continuous galvanizing, as for example, with wire and strip. 1

I have further found that with'the ordinary and usual practice of hotgalvanizing and with many, if not all of the special types ofgalvanizing which have been promoted in recent years, where claims aremade and advanced that the metallic coatings are uniform and smooth andallegedly heavy, that the zinc coatings are far from being heavy andanything but smooth and uniform. This is due to the fact that themethods of. coating do not eliminate oxides adhering to the surface ofthe article and do not eliminate the presence of oxides in the coatingsand'especially the adherence of oxides on the surface of the coatings,and all employ the use of a wipe of some sort or bring the coatedmaterial into contact with some object, in some instances, a skimmerbar, before the coating has had a chance to set; or in some othermanner, move or' deform the coating while in a molten state whichresults in varying thickness of the coating. The presence of theseoxides, wherever they may occur or appear, will ordinarily result inlack of smoothness of the coatings, produce non-uniform coatings andwhen the article is deformed, for whatever purpose, when thesedeformations occur where oxides are present, the coating will crack,break, dust or peel, dueto the varying thickness of the III coatingcaused by the presence of oxides, and

the bath, a substantially oxide free metal. This free oxide metal ispreferably moved from the body of. the metal bath. Immediately on thearticle leaving the bath, it passes into an oxygen free atmosphere,which provides a seal at the exit end .of the bath, and on the coatedarticle leaving such oxygen free atmosphere and. before the coating hasset, I quench the coating with water. Quenching the coating, in thismanner, will effect a stoppage of an alloying action and preventbambooing and rippling surfaces as well as give a bright finish to thearticle and set the coating so that it will not be damaged when passedover pulleys and sheave wheels. In the manner in which I cause the oxidefree metal to flow over and along the surface of the article, aturbulent condition is created on the surface of the bath, at the exitof the material therefrom, and creates or produce an oxide free surface.The presence of oxides on the surface of a bath, where the article iswithdrawn therefrom, will act as a non-uniform wipe which will removemuch of the coating from the article, producing a coating non-uniform inthickness around and throughout its length. However, removing an articlefrom a bath through an oxide free surface created by the fiowing of theoxide free metal thereacross and therearound prevents this condition.Furthermore, to avoid the possibility of adherence of particles ofoxides on the surface of the uncoated article, as it enters the bath,the article may enter the bath through an oxide free surface and bepreliminarily coated with an oxide free coating. -However, the adherenceof. oxide particles to the surface of the articles occurs infrequently,but my method lends itself to the elimination of these particles and maybe used as practice may dictate and is therefore disclosed.

Furthermore, in the production of unwiped wire, where a heavy coating isdesired and where the coated wire is removed vertically from the bath,it is not unusual to find that the coating in its unset state will slipback on the wire and produce a bambooing effect. This will result in anon-uniform thickness of coating which is anything but even. Thisbambooing effect when it is present on sheets, is usually referred to asa roughened rippled surface. I avoid this condition through the speed atwhich the material is moved and quenching the coated article with water,at a predetermined point, after the coated article leaves the bath.

My apparatus lends itself to the heavy coating 7 of rimmed or opensteel, and materials having a decarborized surface.

This application is a continuation in part of the application filed byme May 22, 1933, bearing Serial No. 672,219, for a Method and apparatusfor coating metals.

That the invention may be more fully understood, reference is had. tothe accompanying drawing forming part of this application, illustratinga preferred embodiment of the invention, in which:

Fig. 1 shows in elevation, partly in section, an apparatus forpracticing my invention;

Fig. 2 is a detail taken on the line 2-2, Fig. 1.

Like characters of reference denote corresponding parts throughout thefigures.

In the drawing, the zinc pot is designated l, although only a fragmentof the pot is shown. In galvanizing practice, where it is the aim tocoat a wire with a heavy coating of zinc, for example three-fourths ofan ounce per square foot of surface or more, the wire remains in thezinc bath for long periods, so as to build up an iron zinc alloy toproduce a heavy zinc coating. To carry this out economically, a long potis used and the wire is drawn through the zinc bath at slow speeds andusually the temperature of the bath is increased above the normalworking temperature of the bath. In the instant invention, a heavy zinccoating is produced and this is accomplished by employing a short bath,and high speeds resulting in the material remaining in the bath a shorttime and normal bath temperatures are used. It is pointed out that inthe instant invention the coated wire is quenched with water immediatelyon the coated wire leaving the bath and before the heat of the basemetal acts to increase the iron zinc alloy, the result of which producesa coating low in iron. It has been my experience that where excessiveamounts of iron are present in the coating, if the coated article isquenched too soon, cracking of the coating results. In my invention,quenching of the coated article, as soon as possible after the articleleaves the bath stops the formation of iron zinc alloys and leaves thecoating bright and ductile. It has been my observation with the use ofzinc as a coating that zinc substantially free from iron is very ductileand that the presence of even small amounts of iron reduces theductility and bending qualities of the zinc and of course, withincreasing amounts of iron in the zinc, this condition is aggravated.The average analyses of zinc coating stripped from coated materials showthe iron content as high or higher than dross. Those who are familiarwith the art realize the brittleness of dross. my invention show theiron very low, sometimes less than 2% and free from the objectionsheretofore noted. While I have specifically mentioned Analyses ofcoatings produced by wire, the conditions I have referred to will pre--,

vail, where zinc is used as a coating for iron or steel articles andthis applies to sheets, plates and strip.

A preferred form of apparatus, such as may be employed for practicing myinvention, will now be described. This apparatus is a unit adapted to besupported on the zinc pot I, as shown in Fig. 1.' This unit comprises apan or tray, which is shallow as compared to the depth of the pot and issupported on the pot so that the greater portion of said pan or tray ispartially submerged in the bath. This pan or tray is made up of the sidewalls 2, end walls 3 and 3, and a bottom 5. The latter is shown inclineddownwardly and rearwardly, and adjacent the wall 4 is formed or providedwith 21. depending tubular extension 6,

'line designated as A. The portion 8 of the bottom wall of the pan orvat is shown provided with an opening 9 with the front wall of theopening inclined downwardly, as indicated at Iii. This opening is of alength, across the pan or tray, to

accommodate as many wires, as may be desired and the width of theopening is such as to accommodate the location of the lower end of anopen ended vertically disposed housing l2 through which coated wires Bwill travel, on leaving the bath. This housing is of sufficient width toaccommodate the necessary number of wires being coated, but is ofshallow width in a transverse direction, as will be seen. The front andrear walls of the housing l2 converge toward each other, at both thelower and upper ends of the housing, for purposes to be described. It ispointed out, however, that the location of the lower. end of the housingl2 in its relation to the opening 9 in the bottom wall portion 3 of thepan or vat restricts the opening 9 at .the front of the housing, muchmore than appears at the opposite side, for purposes to be explained.The

housing I2 is supported at or near its lower end from the side walls 2of the pan or vat by braces l3 and from a super-structure, at its upperend, to be described. The housing I2 is of less width than the width ofthe pan or tray, between its side walls 2, for purposes to be explained.The rear wall 4 of the pan or vat I2 is cut lower than the opposite wall3 to provide an overflow for the molten metal, at the rear end of saidpan-or vat and the top of this rear wall 4 is the normal metal line inthe pan or vat, as designated by the dotted line a. An overlying cap orshed is provided for the overflow top of the wall 4, as shown. The loweredge of the front wall of this cap or shed is submerged below the levela of the moltenmetal in the pan or vat to prevent oxides or otherdeleterious substances over-flowing thewall 4.

The pan or vat, at its front end is provided with a dependingcompartment formed with depending side walls I5 and front and rear endwalls l6 and H, but with no bottom wall and being submerged within themolten metal of the bath provides a seal for this portion of the bath.The side walls l5 are extensions of the side walls 2 and the end walll'l connects with and de-v pends at.right angles from the outer end ofthe bottom wall 5. The end wall It connects with the side walls 2 butdoes not extend to the full height of the side walls 2 and the spacebetween the end walls 3 and I6 are connected by a closure which includesa clean out door pivoted at l9 to enable an operator or attendant tohave access to the compartment for observation and clean-out purposes.Some oxides or other deleterious substances, if any, which may collectcan thereby be easily removed. It is entirely probable that some' oxidesor other deleterious substances may be in the bath and if so they willconstantly arise in anupward direction and this provision is made fortheir removal. Disposed within this compartment is a rotatable multiplewinged scraper and valve 20 carried by a shaft 2| journaled in the sidewalls [5 and by means of which the scraper and valve may be rotated. Amanual operating means, not shown, may be connected with an exposed endof this shaft for operating the same. The pan or vat, at its rearend,,is provided with a depending compartment formed with side and endwalls, but with no bottom wall and be-- ing submerged within the moltenmetal of the bath to provide a seal for this portion of the bath. Theside walls are designated 22 and are extensions of the side walls 2. Thefront wall is the wall 4 and its rearwall is the wall 23 which, however,is not of the full heightmf the side walls 2. The top wall of thiscompartment comprises the converging downward and inwardly inclinedportions 24 and 25, the former connectthe wall portion 24' and spacedtherefrom is a wall 26 which together provide an outlet channel 24' forthe overflowing molten metal carried over the top of the wall 4 from thepan or vat which finds its way beneath the cap or shed l4 and into themain bath through this compart- "ment. Inclined similarly to the wallportion 25 and spaced therefrom is a wall 21, which together providepreferably a gas chamber 25" opening journaled in the side wall 22. Thisscraper and valve 30 functions in the same manner and for the samepurpose as the scraper and valve 20. As I have heretofore stated and asis well known to those skilled in the art, the adherence of particles ofoxides and other deleterious substances to the surface bf the base to becoated, as it enters the molten bath, is so infrequent, the compa'rtmentand its appurtenances lastdescribed may or may not be used, except theoverflow feature and a channel to conduct such overflow back into themain bath, the outlet end of which, of course, being submerged withinthe main bath. The troublesome threading of the wire-therethrough, also,may not compensate for theprevention of the infrequent adherence of theparticles of oxide and other deleterious substances to the surface ofthe article being coated and therefore may or may not be used. This 1reduce-the amount of skimmings accumulating in the main bath.

The super-structure, to which reference has been made, and from whichthe upper end of the housing I2 is supported comprises supports 32connected to and upstanding from'the pan or vat. These supports carry awater box 33 having a main chamber 34, a pressure chamber 35 and anoverflow chamber 36. An outlet or discharge 31 from the overflow chamberis shown. Discharge outlets 38 from the pressure chamber are shown.Although not shown, these outlets may be few or many, as desired,depending on the character and kind of coated material to be quenched. Adrain 38 is provided at the front end of the water box 33 and issupported thereby. This drain receives the water from the pressurechamber, which is employed to quench the coated material. trudingthereinto the upper endof the housing I2} as shown and from the drainleads discharge 55 This drain also has prothrough with little or nowater collecting in the drain. The water will not only be applieddirectly to the coated wires but will also envelope and run down thewires; The upper end of the housing 92 is within the drain and hasinwardly converging end walls, such walls will deflect water oh of thetop of the housing into the drain. What small amount of water which maypossibly enter the housing, on the wire, provides a longer coolingdistance and steaming off passes Within the water box and the mainchamber 34 thereof are located a plurality of sheave wheels 42, arrangedside by side, one for each wire, and these sheave wheels are looselyjournaled on a flxed shaft 43 carried by boxings at each side of thewater box. Located in front of the sheave wheels 42 and coincident withthe main chamber 34, but above the pressure chamber 35 are a pluralityof smaller sheave wheels 44, arranged side by side, one for each Wire,and these sheave wheels are loosely journalcd on a fixed shaft 45carried by boxings at each side of the water box. Wires which pass upthrough the housing 12 pass over sheave wheels 44 and down around andover the sheave wheels 42. Water is supplied from a suitable source to afeed pipe 46 and from the feed pipe water is supplied to the pressurechamher through a feeder 41 which empties into the pressure chamber atthe point 48. For each sheave wheel 44, there is a feeder 49 which isconnected to and receives water supplied to it from the feed pipe 46.Water accumulating in the main chamber 34, fed by the feeders 49 willoverflow into the overflow chamber 36 and find its way to a drainthrough the discharge 31. The water accumulating in the main chamber 34of the water box will act to further cool the coated material, whichpasses therethrough. The water discharged by the feeders 49 supplementsthe I water passing out of the pressure chamber and accumulating on thesheave wheels 44 provides a film of water for the passage of the wiresover these sheave wheels. Some of this water finds its way down andaround the wires but thc major portion drains off of the sheave wheels44 into the main chamber of the water box.

The housing l2 constitutes a gas chamber whereby to provide an oxygenfree atmosphere through which the coated wires will pass on leavingthemolten metal bath. This chamber may receive such deoxidizing gas fromany suitable source of supply through a feed pipe 50 from which extendsa feeder 5| in communication with the interior of the housing I2. Also afeeder 52 connects with said feed pipe 50 and is connected to dischargesuch deoxidizing gas into the compartment to one side and below thelower end of the housing l2 in communication with such compartment. Thegas chamber provided by the walls 25 and 21 at the inlet end of the potI may also be fed with deoxidizing gas through a feede 53 which may haveconnection, not shown, with the feed pipe 50 or may have a directconnection, not shown, with the source of supply.

Located in the depending tubular extension 6, which opens into the maincoating bath is a propeller 54 so designed that when rotated, it willpropel oxide free molten metal from within the body of the bath upwardlyand over the inclined bottom of the pan or vat to and down through theopening 9 in the bottom wall 8 and down and around the lower end of thehousing i2 and move across as well as down and around the wires, movingupwardly out of the body of the bath. This propeller is carried on thelower end of a vertically disposed operating shalt 55 which, at itsupper end, is connected to and driven'from a small electric motor 56 orother suitable power unit. The motor may be supported in any suitablemanner, not shown, from the water box and the shaft may be guided andhave journal bearing in the bearings I! and I. Metal overflowing fromthe pan or vat will pass over the top of the wall 4 and beneath the capor shed I4 down through the channel provided by the walls 24 and 26 andinto the main bath.

Within the pot l and submerged within the molten metal is a guide 59,preferably a roller carried by a shaft 60 journaled in the side walls ofthe pot. The apparatus which I have elected to show is designedprimarily for the galvanizing of wire. To employ the same forgalvanizing sheet material, as for example, sheets, strip and the like,some slight modifications would be made, which, however, would notchange the principle of invention involved and it is not thought necessay to extend the drawing to that extent, since those skilled ingalvanizing practice will be able to practice the invention for the usesintended.

To thread the apparatus with wire, the wires B, of whatever number wouldbe threaded down through the gas chamber 25' at the inlet end of thepot, assuming it is desired to employ this structure, otherwise thewires would be directed into the inlet end of the pot over some suitableguiding means, and thence down and around the roller 58. This roller isso located in the pot that the wires may leave the roller and movepreferably upwardly leaving the molten metal bath and travellingperpendicularly through the housing l2 and without contact with anymechanical part or surface contact or rubbing element until the sheavewheels 44 are reached. By this time the quenching action of the waterhas so set the coating that the frictional contact of the sheave wheels44 and 42 have no upsetting or disturbing effect on the coating.

During the coating operation, the motor 56 is set in motion which willrotate the propeller 54 causing an upward movement of the oxide freemetal from the body of the bath into and throughout the pan or tray andflowing down through the opening 9 in the bottom wall portion 8 of thepan or tray and overflowing the wall 4, beneath the cap or shed I4 andback into the bath through the channel 24'. The wires entering the bathwill cross the flow of the metal flowing back into the bath which willenvelope the Wires as they enter the surface of the bath. The wiresenter the pot through an oxygen free atmosphere, provided by the gaschamber 25' into which deoxidizing gas is introduced through the feeder53. This gas will be drawn or sucked down and onto the surface at theinlet end of the bath by the inflow of the overflow metal and seal thesurface of the bath within the compartment below the channel 24 and thegas chamber 25' and thereby provide an oxide free surface at theentrance end of the bath and prevent the formation or adherence ofoxides or deleterious matter on the surface of the wire to be coated.The pressure of the gas itself will supplement this seal.

The oxide free metal which is circulated through the pan or tray by thepropeller 54 will flow down and back into the bath through the opening 9into which projects the lower end of the housing I2. This opening issuch that the down flowing metal will flow down and back into the bathproper from both sides of said housing, somewhat as indicated by thearrows. The lower opposite beveled or inclined side walls of the housingI2 together with the arrangement of the walls of the opening in theirrelation to the housing provides that the down flow of the metal throughthe opening 9 at the rear side of the housing shall be across the wiresmoving upwardly from the surface of the bath into the housing l2, sothat the down flowing metal will completely envelope and run down thewires into the bath. This will tend to cause a more or less turbulentcondition at this point within the bath. The metal flowing down into themain bath at the 10 front side of the housing 12 is in a more or lesseffect or disturbance of the coating.

downward direction and not so much across the wires and will alsoproduce a turbulent condition. These turbulences will keep the surfaceof the bath, where the wires leave the bath, oxide free, because, ifperchance there may be even small particles of oxide or otherdeleterious substances, they will be moved away presenting asubstantially clean surface where the wires emerge from the bath.

0n the wires leaving the bath, they enter an oxygen free atmosphereprovided by the housing I2 which is supplied with a suitable deoxidizinggas. This gas is drawn or sucked down onto the surface of the bathbeneath and within the) compartment therebeneath, which is also suppliedwith gas in the manner described. The result is, that the surface of thebath within the compartment is sealed insuring that the wires leavingthe bath pass out through an oxide clean surface. The pressure of thegas itself will supplement the seal within the compartment.

The wires after they leave the roller 59 are prevented from contact withany mechanical or rubbing surfaces, which would disturb or upset thecoating, until after the coating is quenched immediately on emergencefrom the oxygen free atmosphere, which will then have no upsetting Inthis manner there is assured a substantially oxide free, heavy, uniform,bright and ductile coating which is high in electrical conductivity. Acoating low in iron is also assured because of the short immersion, byreason of the use of a small pot, the speed at which the material ispassed through the pot and the rapidity with which the coated article iscooled.

Emphasis is placed upon the fact that oxide free metal is continuouslysupplied to the pan or vat from within the body of the molten metal andfrom beneath the oxide surface of the metal in the pot I and that thedowniiow of the metal onto the emerging wires is from deep within thebodyof the metal in the pan or vat and from below the surface of themetal in said pan or vat. The accumulation of oxides and otherdeleterious matter on the surface, of the metal in the pan or vat willbe removed from time to time, as occasion requires. The surface of themetal in the pan or vat could, of course, be covered with a suitableflux to retard or prevent the formationof oxides. Such a flux, ofcourse,would not come into contact with the wires.

The scraper and valve 20 and likewise the scraper and valve 30 areprovided and arranged so that they may, when rotated, move or convey anyoxides which may form in either of the designated compartments towardthe closures or clean-outs, to be removed when such closures are opened.When these closures are opened, the scrapers or valves w uld'be set inthe positions shown to prevent the escape of gas.

In hot galvanizing, especially with wire, the- 'base'metal is usuallymoist resulting from the pickling solution or fluxes. Such moisturebeing within the bath which constantly arise in an upward direction andmay beremoved from the designated compartments, from time to time, inthe manner shown.

What I claim is: a i

1. An attachment for a pbt containing molten zinc, comprising a supportadapted for association with said pot, a pan connected with said supportand, when said support is located on said pot being partially submergedwithin the molten zinc, a compartment depending from one end of said panand opening into the molten zinc and having an overlying wall having anopening for the passage of wires therethrough, a vertically disposedhousing coincident with said opening and communicating with saidcompartment, means to supply the housing with a non-oxidizing gas, awater box supported above said pan, a drain at one end of said water boxwith which the upper end of said housing communicates, discharge outletsfrom said water box into said drain, wire guiding sheave wheelsiournaled to rotate within said water box, means to supply water ontocertain of said she'ave wheels, a propeller within said pan and within adepending open tubular extension therefrom, and means for operating saidpropeller.

2. An attachment for a pot containing molten zinc, comprising a supportadapted for association with said pot, a pan connected with said supportand when said support is located on said pot being partially submergedwithin the molten zinc, a compartment depending from one end of said panand opening into the molten zinc ,and having an overlying wall having anopening for the passage of wires therethrough, a vertically disposedhousing coincident with said compartment, means to supply the housingwith a mom oxidizing gas, a water box supported above said pan, a drainat one end of said water box with whichthe upper end of said housingcommunicates, discharge outlets from said water box into said drain,wire guiding sheave wheels journaled to rotate within said water box,means to supply water onto certain of said sheave wheels, a propellerwithin said pan and within a depending open tubular extension therefrom,means for operating said propeller, and an overflow outlet opening intothe molten zinc and having an overlying wall having an opening for thepassage of wires therethrough, a vertically disposed housing coincidentwith said opening and communicating with said compartment, meansto-supply the housing with a non-oxidizing gas, a water box supportedabove said pan, a drain at one end of said water box with which theupper end of said housing communicates, discharge outlets from saidwater box into said drain, wire guiding sheave wheels journaled torotate within said water box, means to supply water onto certain of saidsheave wheels, a propeller withintsaid pan and within an open tubularportion, and means for operating said propeller. I

4. An attachment for a pot containing molten zinc, comprising a supportadapted for association with said pot, a pan connected with said supportand when said support is located on said 10 end of said housingcommunicates, discharge outlets from said water box into said drain,wire guiding sheave wheels journaled to rotate within said water box,means to supply water onto certain of said sheave wheels, a propellerwithin said pan and within an open tubular portion, means for operatingsaid propeller, and an overflow outlet from the end of said pan adjacentthe location of said propeller.

JOSEPH. L. HERMAN. 10

